Carbon-based catalyst for green hydrogen production and simultaneous organic transformation: towards sustainable energy access Soumyadeep Saha Department of Chemical Sciences, Indian Institute of Science Education and Research, Berhampur, India The escalating demand for electricity, driven by expanding populations, underscores the imperative to transition towards renewable energy sources. However, renewable energy currently accounts for only 30 percent of total energy consumption, with solar energy contributing just 13 percent. The limited utilization of solar energy is primarily attributed to nighttime unavailability and storage challenges. Our research proposes a solution that aligns with the goal of ensuring access to affordable, reliable, sustainable, and modern energy. We explore the concept of water splitting, a method harnessing photons to produce hydrogen from water, which can subsequently be stored through hydrogenation. This process, although energetically uphill, holds immense promise for sustainable energy generation. To facilitate this sustainable energy pathway, we focus on designing catalysts capable of photon absorption and providing the essential electrons and holes for water splitting. Carbon nanomaterials, including graphene and carbon nitride, emerge as cost-effective catalysts with remarkable visible light absorption and water splitting capabilities. In our study, we intrinsically modify pristine carbon nitride (C x N y ) by introducing a carbon ring region, substantially enhancing its visible light absorption capabilities, as reported previously 1 . This modified catalyst is employed for photocatalytic green hydrogen production from water splitting, achieving an impressive rate of 1.13 mmole/g in just 4 hours. We assess the role of charge carriers at the water-catalyst interface using photocurrent measurements, revealing significant enhancement under irradiation, credited to the carbon ring region's electron capture for water splitting's reduction half. Findings are reinforced by steady-state and time-dependent Photoluminescence Spectroscopy, indicating reduced radiative recombination and shorter lifetime. Band position analysis via XPS-valance band spectra and Mott-Schottky analysis underscores improved light absorption and reduced overpotential. Expanding clean energy applications, we deploy this catalyst for real-life clean energy production from seawater, achieving up to 0.9 mmole/g hydrogen in 4 hours. Though the production rate reduction is attributed to increased overpotential resulting from seawater salt-induced pH changes, it showcases the versatility of our solution. Furthermore, we explore the catalytic potential of holes by concurrently implementing them in organic transformations alongside green hydrogen production. Utilizing substrates like 4-methyl benzyl alcohol, 4-methoxy benzyl alcohol, and furfuryl alcohol, our catalyst enables oxidation, achieving simultaneous hydrogen production rates of 7 mmole/g, 4 mmole/g, and 1 mmole/g, respectively. In summary, our research introduces a carbon-based catalyst with dual-mode photocatalytic activities, addressing the pressing need for sustainable energy access. This innovative approach offers an economical pathway for green hydrogen production through water splitting while simultaneously yielding industrially significant organic products, thus promoting the attainment of affordable, reliable, sustainable, and modern energy access. References 1. Che, W., Cheng, W., Yao, T., Tang, F., Liu, W., Su, H., Huang, Y., Liu, Q., Liu, J., Hu, F., Pan, Z., Sun, Z., & Wei, S. (2017). Fast Photoelectron Transfer in (Cring)–C3N4 Plane Heterostructural Nanosheets for Overall Water Splitting. In Journal of the American Chemical Society (Vol. 139, Issue 8, pp. 3021–3026). American Chemical Society (ACS). https://doi.org/10.1021/ jacs.6b11878
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